Inverter control method and its device

ABSTRACT

An inverter controlling apparatus comprises a conventional condenser-less inverter controlling section  11  for outputting a provisional torque command or current for torque command for controlling a conventional condenser-less inverter, i 1 * operation section  12  for receiving a motor torque τ m , motor rotational speed ω m , power voltage v 1 , and coefficient η as inputs, for calculating a power current i 1  by carrying out operation of equation (10), and for outputting the power current i 1  as power current command value i 1 *, feedback operation section  13  for receiving the power current command value i 1 * and the real current i 1  as inputs, for carrying out operation so as to make the deviation between the both to be 0 (for example, PI operation), and for outputting the torque command for correction or current for torque command for correction, and subtraction section  14  for subtracting the torque command for correction or current for torque command for correction which is output from the feedback operation section  13 , from the provisional torque command or current for torque command which is output from the conventional condenser-less inverter controlling section  11 , and for obtaining a final torque command or current for torque command, so that controlling is carried out for suppressing the capacitor current thereby distortion of the power current is suppressed.

TECHNICAL FIELD

[0001] The present invention relates to an inverter controlling method and apparatus thereof. More particularly, the present invention relates to a method and apparatus for controlling a three-phase inverter, for supplying output voltages or output currents of the three-phase inverter to a motor, which method and apparatus include therein a single phase rectification circuitry and the three-phase inverter and determine a capacitance of a capacitor connected between output terminals of the single phase rectification circuitry so as to pulsate an output voltage of the single phase rectification circuitry by a frequency which is twice of a power frequency.

BACKGROUND ART

[0002] As is known from the past, an inverter circuitry is a circuitry which transforms a DC power into an AC power with variable frequency and variable voltage with high efficiency by switching controlling of transistors.

[0003] And, an inverter circuitry is widely applied to home electric devices and industrial devices which are required controlling of rotation numbers or a torque of a motor, for example.

[0004] In general, a diode-bridge circuitry having a simple circuit configuration is employed for transforming an AC power into a DC power, and a smoothing capacitor having a large capacitance is employed for removing voltage ripples which appear in rectified voltage.

[0005] In this case, disadvantages arise such that a power factor in power side is lowered, and harmonics are increased. For preventing or suppressing such disadvantages, a power factor improvement reactor having a large inductance is connected to input side or DC side of the diode-bridge circuitry (refer to FIG. 18).

[0006] In recent years, it is proposed that a chopper comprising a transistor, diode and the like, is provided in the DC side of the diode-bridge circuitry, for the purpose of improvement in characteristics for power source power factor and power source harmonics (refer to FIG. 20).

[0007] When such inverter circuitry is employed, a smoothing capacitor having a large capacitance and a power factor improvement reactor are needed. Therefore, disadvantages arise such that a size becomes greater following the employment of those elements, and increase in cost is realized.

[0008] For realizing high performance in power source harmonics characteristics, a chopper circuitry is further needed. Therefore, further increase in cost is realized.

[0009] An electrolytic capacitor is generally employed as the smoothing capacitor having a large capacitance. Therefore, disadvantages arise such that a lifetime of an inverter circuitry including a diode-bridge circuitry becomes shorter due to a short lifetime of an electrolytic capacitor, and usage environment of an inverter circuitry including a diode-bridge circuitry is limited due to thermal characteristics of an electrolytic capacitor.

[0010] To dissolve those disadvantages, an inverter controlling method is proposed (refer to “Inverter controlling method of a PM motor having a diode rectification circuitry with a high input power factor”, Isao Takahashi, Heisei 12 nen (2000) denkigaklcai (Electronics Institute) zennkoku taikai (national convention), p1591, which is referred to Article 1 hereinafter). The inverter controlling method realizes increasing input power factor and improvement in performance of power source harmonics characteristics by allowing motor currents flowing into a motor even when a DC voltages pulsates and greatly lowered, and consequently widening a conduction width of an inverter input (input of a rectification circuitry) which are due to omitting a smoothing capacitor having a large capacitance in a rectification section, varying a d-axis current with a frequency which is twice of a power frequency, lowering motor terminal voltages by field weakening control.

[0011] When this method is employed, an input power factor of a rectification circuitry is improved by controlling an output of an inverter connected to the rectification circuitry to have a desired waveform. Decreasing in power source harmonics can be expected. Therefore, an electrolytic capacitor having a large capacitance, reactor, and chopper become unnecessary which are conventionally necessary to realize those advantages.

[0012] Further, “High efficiency inverter controlling method of IPM motor with weak field”, Jin Haga, Isao Takahashi, Heisei 13 nen (2001) denkigakkai. (Electronics Institute) zennkoku taikai (national convention), p1214 (referred to Article 2 hereinafter) is proposed as a controlling method based upon the Article 1.

[0013] When the inverter circuitry having the arrangement of FIG. 18 is employed, an AC power is rectified by the diode-bridge rectification circuitry, and is smoothened by the electrolytic capacitor having a large capacitor (for example, about 2000 μF for motor capacitance of 2.2 kW). This smoothened output is supplied to the inverter for driving the motor.

[0014] When an inverter circuitry is employed for home devices, a reactor (about 3.5 mH when a capacitance of a capacitor is 2000 μF) is connected between a rectification circuitry and a capacitor, or between an AC power and a rectification circuitry, for improving a power factor.

[0015]FIG. 19 shows the DC voltage (the voltage between both terminals of the electrolytic capacitor) V_(dc), the power current (the current flows from the AC power to the rectification circuitry) i₁, the absolute value |v_(i)| of the AC voltage obtained by the rectification of the rectification circuitry, and a fundamental component of the power current i_(i) of the inverter circuitry of FIG. 18. The absolute value |v_(i)| of the AC voltage and the fundamental component of the power current i₁ are not values which are directly measured from the, inverter circuitry.

[0016] φ in FIG. 19 represents a phase difference between the AC voltage v_(i) and the fundamental wave of the power current i₁, that is a power factor.

[0017] The power factor cos φ of the inverter circuitry of FIG. 18 is low and is up to about 80% (φ=37°. When the magnitude of the absolute value |v_(i)| of the AC voltage exceeds the smoothened voltage V_(dc) between terminals of the electrolytic capacitor, the diode of the rectification circuitry turns on and the power current i₁ flows therein. Therefore, the waveform of the power current i₁ is deformed, and the magnitudes of low harmonics (third, 5-th, 7-th, and the like) are extremely large which are obtained by the harmonic analysis of the power current i₁, which are not illustrated. A reactor having a large inductance value is needed for a filter for eliminating low harmonics. Therefore, disadvantages arise such that increase in cost, and increase in entire size of the inverter device.

[0018] An inverter circuitry of FIG. 20 further includes a chopper circuitry comprising a transistor T_(c) and diode D_(c). By controlling the transistor T_(c) to turn on, the power current can be flows therein even for a period when the power current i₁ does not flow therein for the inverter circuitry of FIG. 18 (a period when the voltage V_(dc) between terminals of the electrolytic capacitor exceeds the amplitude of the absolute value |v_(i)| of the AC voltage). And, the power current i₁ can be made to have a sine shape by adequately controlling the on-duty of the transistor T_(c). Reverse flow of the current from the capacitor to the transistor T_(c) is prevented by the diode D_(c).

[0019] But, the inverter circuitry of FIG. 20 requires not only the transistor T_(c) and diode D_(c) but also a circuitry for controlling the transistors T_(c) in comparison with the inverter circuitry of FIG. 18. Therefore, it becomes very difficult that the inverter circuitry of FIG. 20 is employed in home electric devices.

[0020]FIG. 21 shows an inverter circuitry disclosed in the Article 1 for dissolving those problems.

[0021] The inverter circuitry of FIG. 21 is different from the inverter of FIG. 18 in that a capacitor having small capacitance (for example, a capacitor having capacitance of about {fraction (1/100)} capacitance value) is employed instead the electrolytic capacitor having large capacitance.

[0022] When the inverter circuitry of FIG. 21 (hereinafter, referred to as condenser-less inverter circuitry) is employed, the DC voltage changes from V_(max) (the maximum value of the power voltage v₁) to V_(min), determined in correspondence with the induction voltage generated by the motor along the absolute value |v_(i)| of the power voltage, as is illustrated in FIG. 22, by adequately controlling the currents flowing in the motor through the inverter, because the capacitance of the capacitor is very small. Wherein, V_(min) can be controlled by the field control of the motor.

[0023] As a result, waveform distortion of the power current i₁ becomes smaller with respect to the case of FIG. 19.

[0024] When the flowing period of the power current i₁ is determined to be θ, the power factor cos φ can be calculated by an equation (1).

cos φ={square root}{square root over ((θ+sin θ)/π)}  equation (1)

[0025] From the equation (1), the power factor (cos φ) becomes equal to or more than 97% when V_(max)/V_(min){(=cos(ƒ/2)}>2.

[0026]FIG. 23 is a block diagram illustrating an arrangement of an inverter controlling apparatus for controlling an IPM motor using the inverter circuitry of FIG. 21 and for implementing the controlling method disclosed in the Article 2 for obtaining desired performance.

[0027] This inverter controlling apparatus comprises a PI operation section 111, sin² θ₁ generation section 112, and q-axis current command operation section 110. The PI operation section 111 receives a deviation of a speed command ω_(m)* and a real motor speed ω_(m) as an input, and outputs a value |i_(q)*| by carrying out PI operation (proportional and integral operation). The sin² θ₁ generation section 112 receives a power voltage v₁ as an input and outputs a signal sin² θ₁ which is in synchronism with the power voltage. The q-axis current command operation section 110 obtains a product of the signal sin² θ_(i) and the value |i_(q)*|, and outputs the product as a q-axis current command i_(q)*.

[0028] This inverter controlling apparatus further comprises an i_(d)* operation section 114, PI operation sections 115 and 116 for d-axis and q-axis, and a non-interacting controlling section 117. The i_(d)* operation section 114 receives a DC voltage V_(dc), q-axis current i_(q), and a real motor speed ω_(m) as inputs, and outputs a d-axis current command i_(d)* by carrying out the operation of equation (2). The PI operation sections 115 and 116 receives deviations of dq-axes current commands i_(d)* and i_(q)* and dq-axes real currents i_(d) and i_(q) and output first dq-axes voltage commands v_(d)* and v_(q)* by carrying out PI operation. The non-interacting controlling section 117 receives the first dq-axes voltage commands v_(d)*′ and v_(q)*′ as inputs and outputs second dq-axes voltage commands v_(d)* and v_(q)* by carrying out the operation of equation (3). $\begin{matrix} {{i_{d}^{*} = {{- \frac{\lambda_{a}}{L_{d}}} + \sqrt{\left( \frac{vdc}{n \cdot \omega_{m}} \right)^{2} - \left( {L_{q} \cdot i_{q}} \right)^{2}}}}} & {{Equation}\quad (2)} \\ {{v_{q}^{*} = {{v_{q}^{*}}^{\prime} + {\left( {\lambda_{a} + {L_{d} \cdot i_{d}}} \right) \cdot n \cdot \omega_{m}}}}{v_{d}^{*} = {{v_{d}^{*}}^{\prime} - {L_{q} \cdot i_{q} \cdot n \cdot \omega_{m}}}}} & {{Equation}\quad (3)} \end{matrix}$

[0029] It is thought that the power current i₁ illustrated in FIG. 22 can be obtained when the inverter controlling apparatus of FIG. 23 is employed, and when the q-axis current is controlled to be i_(q)*

sin² θ₁.

[0030]FIG. 24 is a diagram illustrating waveforms in a case that a DC voltage (voltage between both terminals of a capacitor) is controlled from V_(max) to 0 by the field control of a motor. For convenience, a phase θ₂ is applied Fourier transformation by determining a phase to be 0° (360°) which corresponds to the maximum value of the DC voltage V_(dc), so that an equation (4) is obtained. $\begin{matrix} {{v_{d\quad c} = {\frac{2 \cdot V_{\max}}{\pi}\left\{ {1 + {\sum\limits_{n = 1}^{\infty}{{\left\lbrack {\frac{\left( {- 1} \right)^{n}}{{2n} + 1} + \frac{\left( {- 1} \right)^{n + 1}}{{2n} - 1}} \right\rbrack \cdot \cos}\quad n\quad \theta_{2}}}} \right\}}}{{Wherein},{\theta_{2} = {2\quad \bullet \quad \theta_{1}\quad \left( {\theta_{1}\quad {is}\quad a\quad {power}\quad {voltage}\quad {phase}} \right)}}}} & {{Equation}\quad (4)} \end{matrix}$

[0031] A magnitude of a current amplitude becomes an equation (5) which current flows through a capacitor due to an AC component in a DC voltage V_(dc). $\begin{matrix} {{{i_{chn}} = {{2{\pi \cdot f_{2n} \cdot C \cdot {v_{dchn}}}} = {4 \cdot f_{2n} \cdot C \cdot V_{\max} \cdot \left\{ {\frac{\left( {- 1} \right)^{n}}{{2n} + 1} + \frac{\left( {- 1} \right)^{n + 1}}{{2n} - 1}} \right\}}}}{{herein},{f_{2n} = {2\quad \bullet \quad n\quad \bullet \quad f_{1}\quad \left( {{f_{1}\text{:}\quad {power}\quad {frequency}},{n = 1},2,{3\quad \bullet \quad \bullet}}\quad \right)}}}} & {{Equation}\quad (5)} \end{matrix}$

[0032] When V_(max)=283 V (power voltage effective value=200 V, power frequency is 50 Hz), an amplitude V_(dch1) of twice frequency component with respect to a power frequency (n=1 in the equation (4)) becomes 120 V.

[0033] When a capacitance of a capacitor is determined to be 20 μF which is {fraction (1/100)} of the conventional capacitance, a magnitude of the current becomes |V_(ch1)|=1.5 A from the equation (5). And, the phase becomes a phase which is illustrated in FIG. 24.

[0034]FIG. 25 shows an ideal controlling waveform thought in the Article 2 (a power current i₁ when a DC voltage v_(dc) can be adjusted from 0 to V_(max)), capacitor current i_(ch1), and a distortion of a power current waveform when only the controlling of the Article 2 is carried out that is no compensation is made for the capacitor current i_(ch1). In practice, i_(ch2), i_(ch3),

flow, but illustration is omitted for convenience.

[0035] That is, in the inverter controlling apparatus of FIG. 21, the DC voltage v_(dc) greatly pulsates, includes AC component having a large amplitude. Therefore, currents i_(ch1), i_(ch2), i_(ch3),

which flow into the capacitor from the power source through the single-phase rectification circuitry, are generated so-that the power current waveform is distorted.

[0036] Disadvantage arises that harmonics of the power current (input current) i1 cannot be controlled to be smaller (in ideal, cannot be controlled to be a sine wave) when the capacitor current is not compensated.

[0037] The present invention was made in view of the above problems.

[0038] It is an object of the present invention to provide an inverter controlling method and apparatus thereof which can carry out controlling for suppressing a current flowing into a capacitor from a power source through a single-phase rectification circuitry.

DISCLOSURE OF THE INVENTION

[0039] An inverter controlling method of claim 1 includes a single-phase rectification circuitry and three-phase inverter, determines a capacitance of a capacitor so as to greatly pulsate an output voltage from the single-phase rectification circuitry at twice frequency of a power frequency, which capacitance is connected between output terminals of the single-phase rectification circuitry, and carries out controlling for suppressing the current flowing into the capacitor from the power source through the single-phase rectification circuitry when the three-phase inverter is controlled so as to supply output voltage or output current from the three-phase inverter to a motor.

[0040] An inverter controlling method of claim 2 is a method for controlling the motor for suppressing the current flowing into the capacitor from the power source through the single-phase rectification circuitry.

[0041] An inverter controlling method of claim 3 is a method for controlling torque or current for torque for suppressing the current flowing into the capacitor from the power source through the single-phase rectification circuitry.

[0042] An inverter controlling apparatus of claim 4 is an apparatus which comprises a single-phase rectification circuitry and a three-phase inverter, determines a capacitance of a capacitor connected between output terminals of the single-phase rectification circuitry so as to allow an output voltage from the single-phase rectification circuitry to pulsate at a frequency which is twice of a power frequency, and controls the three-phase inverter so as to supply an output voltage or output current from the three-phase inverter to a motor, the apparatus comprises suppression means for suppressing the current flowing into the capacitor from the power source through the single-phase rectification circuitry.

[0043] An inverter controlling apparatus of claim 5 is an apparatus which comprises a single-phase rectification circuitry and a three-phase inverter, determines a capacitance of a capacitor connected between output terminals of the single-phase rectification circuitry so as to allow an output voltage from the single-phase rectification circuitry to pulsate at a frequency which is twice of a power frequency, and controls the three-phase inverter so as to supply an output voltage or output current from the three-phase inverter to a motor, the apparatus comprises controlling means for carrying out controlling for suppressing the current flowing into the capacitor from the power source through the single-phase rectification circuitry.

[0044] An inverter-controlling apparatus of claim 6 employs controlling means for controlling the motor for suppressing the current flowing into the capacitor from the power source through the single-phase rectification circuitry, as the controlling means.

[0045] An inverter controlling apparatus of claim 7 employs controlling means for controlling a torque or current for torque for suppressing the current flowing into the capacitor from the power source through the single-phase rectification circuitry, as the controlling means.

[0046] An inverter controlling apparatus of claim 8 is an apparatus which comprises a single-phase rectification circuitry and a three-phase inverter, determines a capacitance of a capacitor connected between output terminals of the single-phase rectification circuitry so as to allow an output voltage from the single-phase rectification circuitry to pulsate at a frequency which is twice of a power frequency, and controls the three-phase inverter so as to supply an output voltage or output current from the three-phase inverter to a motor, the apparatus comprises capacitor current operation means for obtaining a capacitor current flowing into the capacitor from the power source through the single-phase rectification circuitry, and current for torque correction means for correcting a current for torque by subtracting the obtained capacitor current from the current for torque.

[0047] An inverter controlling apparatus of claim 9 employs capacitor current operation means for carrying out harmonics analysis for the power current, as the capacitor current operation means.

[0048] An inverter controlling apparatus of claim 10 employs a component of a frequency which is twice of the power frequency, as the harmonics analysis result.

[0049] An inverter controlling apparatus of claim 11 employs capacitor current operation means for outputting the capacitor current based upon the stored pattern, as the capacitor current operation means.

[0050] An inverter controlling apparatus of claim 12 further comprises correction means for correcting the capacitor current based upon the DC voltage detection value, the capacitor current being output based upon the stored pattern.

[0051] An inverter controlling apparatus of claim 13 employs controlling means including phase determination means for determining a phase of the current for torque to be a phase of delay, as the controlling means.

[0052] When the inverter controlling method of claim 1 is employed, the method includes a single-phase rectification circuitry and three-phase inverter, determines a capacitance of a capacitor so as to greatly pulsate an output voltage from the single-phase rectification circuitry at twice frequency of a power frequency, which capacitance is connected between output terminals of the single-phase rectification circuitry, and carries out controlling for suppressing the current flowing into the capacitor from the power source through the single-phase rectification circuitry when the three-phase inverter is controlled so as to supply output voltage or output current from the three-phase inverter to a motor. Therefore, harmonics in the power current can be reduced.

[0053] When the inverter controlling method of claim 2 is employed, the method controls the motor for suppressing the current flowing into the capacitor from the power source through the single-phase rectification circuitry. Therefore, operations and effects similar to those of claim 1 are realized by carrying out torque control of the motor or speed control of the motor.

[0054] When the inverter controlling method of claim 3 is employed, the method controls torque or current for torque for suppressing the current flowing into the capacitor from the power source through the single-phase rectification circuitry. Therefore, operations and effects similar to those of claim 1 are realized by controlling the torque or current for torque.

[0055] When the inverter controlling apparatus of claim 4 is employed, the apparatus comprises a single-phase rectification circuitry and a three-phase inverter, determines a capacitance of a capacitor connected between output terminals of the single-phase rectification circuitry so as to allow an output voltage from the single-phase rectification circuitry to pulsate at a frequency which is twice of a power frequency, and controls the three-phase inverter so as to supply an output voltage or output current from the three-phase inverter to a motor, and suppresses the current flowing into the capacitor from the power source through the single-phase rectification circuitry by the suppression means. Therefore, harmonics in the power current can be reduced.

[0056] When the inverter controlling apparatus of claim 5 is employed, the apparatus comprises a single-phase rectification circuitry and a three-phase inverter, determines a capacitance of a capacitor connected between output terminals of the single-phase rectification circuitry so as to allow an output voltage from the; single-phase rectification circuitry to pulsate at a frequency which is twice of a power frequency, and controls the three-phase inverter so as to supply an output voltage or output current from the three-phase inverter to a motor, and carries out controlling for suppressing the current flowing into the capacitor from the power source through the single-phase rectification circuitry by the controlling means. Therefore, harmonics in the power current can be reduced.

[0057] When the inverter controlling apparatus of claim 6 is employed controlling means for controlling the motor for suppressing the current flowing into the capacitor from the power source through the single-phase rectification circuitry is employed as the controlling means. Therefore, operations and effects similar to those of claim 1 are realized by carrying out torque control of the motor or speed control of the motor.

[0058] When the inverter controlling apparatus of claim 7 is employed, controlling means for controlling a torque or current for torque for suppressing the current flowing into the capacitor from the power source through the single-phase rectification circuitry is employed as the controlling means. Therefore, operations and effects similar to those of claim 1 are realized by controlling the torque or current for torque.

[0059] When the inverter controlling apparatus of claim 8 is employed, the apparatus comprises a single-phase rectification circuitry and a three-phase inverter, determines a capacitance of a capacitor connected between output terminals of the single-phase rectification circuitry so as to allow an output voltage from the single-phase rectification circuitry to pulsate at a frequency which is twice of a power frequency, and controls the three-phase inverter so as to supply an output voltage or output current from the three-phase inverter to a motor. When the above operation is realized, a capacitor current flowing into the capacitor from the power source through the single-phase rectification circuitry is obtained by the capacitor current operation means, and the current for torque is corrected by subtracting the obtained capacitor current from the current for torque by the current for torque correction means. Therefore, harmonics in power current can be decreased by denying the capacitor current.

[0060] When the inverter controlling apparatus of claim 9 is employed, capacitor current operation means for carrying out harmonics analysis for the power current is employed as the capacitor current operation means. Therefore, operations and effects similar to those of claim 8 are realized.

[0061] When the inverter controlling apparatus of claim 10 is employed, a component of a frequency which is twice of the power frequency is employed as the harmonics analysis result. Therefore, operation load can be decreased, and operations and effects similar to those of claim 9 are realized.

[0062] When the inverter controlling apparatus of claim 11 is employed, capacitor current operation means for outputting the capacitor current based upon the stored pattern is employed as the capacitor current operation means. Therefore, operation load can be decreased, and operations and effects similar to those of claim 8 are realized

[0063] When the inverter controlling apparatus of claim 12 is employed, the apparatus further comprises correction means for correcting the capacitor current based upon the DC voltage detection value, the capacitor current being output based upon the stored pattern. Therefore, the capacitor current can be calculated with accuracy, and operations and effects similar to those of claim 11 are realized.

[0064] When the inverter controlling apparatus of claim 13 is employed, controlling means including phase determination means for determining a phase of the current for torque to be a phase of delay is employed as the controlling means. Therefore, compensation of the capacitor current can be carried out easily, and operations and effects similar to those of claim 7 are realized.

BRIEF DESCRIPTION OF THE DRAWINGS

[0065]FIG. 1 is a diagram schematically illustrating a controlling system which includes an inverter controlling apparatus according to the present invention therein;

[0066]FIG. 2 is a block diagram illustrating a main section of an inverter controlling apparatus of an embodiment according to the present invention;

[0067]FIG. 3 is a block diagram illustrating an inverter controlling apparatus of another embodiment according to the present invention;

[0068]FIG. 4 is a block diagram illustrating a main section of an inverter controlling apparatus of a further embodiment according to the present invention;

[0069]FIG. 5 is a block diagram illustrating an inverter controlling apparatus of a further embodiment according to the present invention;

[0070]FIG. 6 is a block diagram illustrating a main section of an inverter controlling apparatus of a further embodiment according to the present invention;

[0071]FIG. 7 is a block diagram illustrating a main section of an inverter controlling apparatus of a further embodiment according to the present invention;

[0072]FIG. 8 is a block diagram illustrating a main section of an inverter controlling apparatus of a further embodiment according to the present invention;

[0073]FIG. 9 is a block diagram illustrating a main section of an inverter controlling apparatus of a further embodiment according to the present invention;

[0074]FIG. 10 are diagrams illustrating a waveform of a DC voltage V_(dc) when the minimum value of a DC voltage V_(dc) is determined to be V_(min) by the field controlling, and a waveform of a DC voltage V_(dc) when light-load is applied;

[0075]FIG. 11 is a block diagram illustrating a main section of an inverter controlling apparatus of a further embodiment according to the present invention;

[0076]FIG. 12 is a flowchart describing power source phase synchronism processing;

[0077]FIG. 13 is a flowchart describing power source phase generation processing;

[0078]FIG. 14 is a flowchart describing current controlling processing;

[0079]FIG. 15 is a flowchart describing an example of conventional processing of the step SP3 in FIG. 14.

[0080]FIG. 16 is a flowchart describing an example of processing according to the present invention of the step SP3 in FIG. 14.

[0081]FIG. 17 is a flowchart describing another example of processing according to the present invention of the step SP3 in FIG. 14.

[0082]FIG. 18 is an electric circuitry diagram illustrating an example of an arrangement of a conventional inverter circuitry;

[0083]FIG. 19 is a diagram illustrating a DC voltage waveform and a power current waveform in the inverter circuitry of FIG. 18;

[0084]FIG. 20 is an electric circuitry diagram illustrating another example of an arrangement of a conventional inverter circuitry;

[0085]FIG. 21 is an electric circuitry diagram illustrating an arrangement of a conventional condenser-less inverter circuitry;

[0086]FIG. 22 is a diagram describing the controlling principal of the condenser-less inverter circuitry;

[0087]FIG. 23 is a block diagram illustrating an arrangement of an inverter controlling apparatus for controlling the conventional condenser-less inverter circuitry;

[0088]FIG. 24 is a diagram illustrating a voltage at the DC section of the condenser-less inverter circuitry, and a current component of a frequency which is twice of the power frequency, the current flowing in the capacitor section of the condenser-less inverter circuitry; and

[0089]FIG. 25 is a diagram illustrating a power current when the condenser-less inverter circuitry is controlled.

BEST MODE FOR CARRYING OUT THE INVENTION

[0090] Hereinafter, referring to the attached drawings, we explain embodiments of an inverter controlling method and apparatus according to the present invention, in detail.

[0091]FIG. 1 is a diagram schematically illustrating a controlling system which includes an inverter controlling apparatus according to the present invention therein.

[0092] This controlling system comprises a diode full-wave rectification circuitry (single-phase rectification circuitry) 2 which receives an AC power source 1 as an input, a capacitor 3 having a small capacitance (for example, a film condenser) which is connected between output terminals of the diode full-wave rectification circuitry 2, an inverter (three-phase inverter) 4 which receives an output voltage from the diode full-wave rectification circuitry 2 as an input, an IPM motor 5 having a rotor 5 b and stator windings 5 a which are supplied outputs from the inverter 4, a position detection section 5 c for detecting a rotational position (magnetic pole position) of the rotor 5 b of the IPM motor 5, input voltage detection section 2 a for detecting an input voltage of the diode full-wave rectification circuitry 2, a power current detection section 2 b for detecting a power current of the diode full-wave rectification circuitry 2, a DC voltage detection section 2 c for detecting a voltage on the output side of the diode full-wave rectification circuitry 2, a zero-cross detection section 2 d for detecting a zero-cross of the input voltage, a controlling microcomputer 6, and a base-driving circuitry 6 a. The controlling, microcomputer 6 receives the position detection signal, motor currents, zero-cross detection signal, power current, DC voltage, and speed command ω* or q-axis current amplitude command I_(qm)* given from the exterior, as inputs, and outputs controlling signals by carrying out predetermined controlling operation. The base-driving circuitry 6 a receives the controlling signals as inputs and outputs switching signals each of which is supplied to each switching transistor of the inverter 4.

[0093] At first, a controlling method is considered in a case that a capacitance of the capacitor 3 included within the controlling system of FIG. 1 is determined to be 0.

[0094] In FIG. 1, when the motor efficiency is represented by η_(M), the main circuitry efficiency (efficiency of the rectification circuitry and inverter) is represented by η_(INV), relationship of equation (6) is established between the inverter instantaneous input P₁ and motor instantaneous output P_(m).

P _(m)=η_(INV)·η_(m) ·P ₁  Equation (6)

[0095] The motor instantaneous output P_(m) can be expressed as equation (7) using the motor speed ω_(m) and torque τ_(m).

p _(m)=ω_(m)·τ_(m)  Equation (7)

[0096] The inverter instantaneous input P₁ can be expressed as equation (8) using the assumption that the power factor is 100%, power voltage v₁ and power current i₁.

p ₁ =v ₁ ·i ₁=2·V₁ ·I ₁·sin²(ω ₁ ·t) v ₁={square root}{square root over (2)}·V ₁·sin(ω₁ ·t), i ₁{square root}{square root over (2)}·I ₁·sin(ω₁ ·t)  Equation (8)

[0097] Wherein, t represents a time, ω₁ represents power source angular frequency, V₁ and I₁ represent effective values of the power voltage and power current, respectively.

[0098] Wherein, the motor efficiency η_(M) and the main circuitry efficiency η_(INV) change depending upon the waveform controlling method of the inverter and the motor output, but they are constant at each operation point. Each efficiency value is supposed to be 100% for simplifying equations in the following discussion. Further, the speed of rotation ω_(1m) of the motor is supposed to be constant, and when the motor torque can be controlled so as to change the motor torque at a frequency which is twice of the power frequency, based upon equation (9) by equations (6) to (8), the inverter power current becomes a sine-wave (waveform without distortion), and controlling of the power factor of 100% is realized. $\begin{matrix} {{\tau_{m} = {{{T_{m} \cdot \sin^{2}}\theta_{1}} = {\frac{1}{2} \cdot T_{m} \cdot \left( {1 - {\cos \quad 2\theta_{1}}} \right)}}}{{Wherein},{\theta_{1} = {{\omega_{1}}^{\prime}\quad \bullet \quad t}}}} & {{Equation}\quad (9)} \end{matrix}$

[0099] When the torque controlling of a motor is carried out based upon the equation (9), velocity ripple is generated following the torque ripple at a frequency which is twice of power frequency. But, the amplitude of the velocity ripple becomes smaller to a value which can be ignored due to inertia effect when the motor rotates at a high speed.

[0100] As an example, a trial calculation is made for a case that moment of inertia of a compressor mechanism and motor: 0.5×10⁻³ kgm², and the power frequency is 50 Hz, the amplitude of the velocity ripple becomes 1 rps under the average torque of 2 Nm (that is, torque ripple amplitude T_(m)/2=2 Nm). When the speed of rotation of the motor is controlled to be 60 rps, the velocity ripple was about 1.6%. From the above, it is confirmed that the speed can be assumed to be constant.

[0101] On the other hand, distortion in power current is generated due to the capacitor current i_(c) given by the equation (5) when the capacitance of the capacitor is not 0 and when controlling is made only as the equation (9).

[0102] To dissolve this disadvantage, it is sufficient that a filter for removing the capacitor current i_(c) when the controlling is carried out based upon the equation (9). In this case, effectively limiting is carried out by the filter so as to remove (suppress) the capacitor current i_(c).

[0103] When the distortion in the power current is dissolved by the controlling, it is sufficient that the motor torque or the motor speed is controlled so as to suppress the capacitor current i_(c) overlapped to the power current.

[0104] Following two construction methods for controlling can be thought.

[0105] a) a method for calculating an ideal power current i₁′ based upon the equations (6) to (8) which flows when the capacitance of the capacitor is 0, when the torque of the equation (9) is generated, and for feedback controlling so as to follow the detection value of the power current i₁ to the calculation result;

[0106] b) a method for determine the torque or current for torque so as to allow a current to flow which is in reversed phase with respect to the capacitor current i_(c), and for feed-forward controlling.

[0107] Hereinafter, description is made in detail for an embodiment for a case that a torque is controlled.

[0108]FIG. 2 is a block diagram illustrating a main section of an inverter controlling apparatus of an embodiment according to the present invention. This inverter controlling apparatus carries out feedback controlling.

[0109] This inverter controlling apparatus comprises a conventional condenser-less inverter controlling section 11, i₁* operation section 12, feedback operation section 13, and subtraction section 14. The conventional condenser-less inverter controlling section 11 outputs provisional torque command or current for torque command for controlling a conventional condenser-less inverter. The i₁* operation section 12 receives a motor torque τ_(m), motor rotational speed ω_(m), power voltage v₁, and coefficient η as inputs, calculates a power current i₁ by carrying out operation of equation (10), and outputs the power current i₁ as power current command value i₁*. The feedback operation section 13 receives the power current command value i₁* and the real current i₁ as inputs, carries out operation so as to make the deviation between the both to be 0 (for example, PI operation), and outputs the torque command for correction or current for torque command for correction. The subtraction section 14 subtracts the torque command for correction or current for torque command for correction which is output from the feedback operation section 13 from the provisional torque command or current for torque command which is output from the conventional condenser-less inverter controlling section 11, and obtains a final torque command or final current command for torque. $\begin{matrix} {i_{1}^{*} = {\frac{\tau_{m} \cdot \omega_{m}}{v_{1}\quad \bullet \quad \eta} = {{\frac{T_{m}}{V_{\max} \cdot \eta} \cdot \sin}\quad \theta_{1}}}} & {{Equation}\quad (10)} \end{matrix}$

[0110] Operation of the inverter controlling apparatus having the above arrangement is as follows.

[0111] The power current i₁ becomes the equation (10) using the equations (6) to (8), when the controlling is carried out so as to be the torque of the equation (9). It is determined to be the power current command value i₁*. The torque command for correction or current for torque command for correction is obtained by carrying out controlling (for example, PI controlling) for malting the difference between the power current command value i₁* and the real current i₁ to be 0. Using this, the provisional torque command or current for torque command is corrected, so that the torque or current for torque is controlled for suppressing the capacitor current. Consequently, distortion in power current can be reduced.

[0112] In the equation (10), the coefficient η is a constant for taking the main circuitry efficiency, motor efficiency and power factor into consideration. For determining the distortion to be 0, the coefficient η may be changed in response to the load torque or rotational speed. For simplifying the controlling operating processing, driving condition of applied devices are taken into consideration so that the value at typical load condition is on behalf of.

[0113]FIG. 3 is a block diagram illustrating an inverter controlling apparatus of another embodiment according to the present invention.

[0114] This inverter controlling apparatus comprises a PI operation section 21, sin² θ₁ generation section 22, multiplication section 23, i_(d)* operation section 24, PI sections 25 and 26 for d-axis and q-axis, and decoupling controlling section 27. The PI operation section 21 receives a deviation between the speed command ω_(m)* and the motor real speed ω_(m) as an input, and outputs a value of |i_(q)*| which is obtained by carrying out the PI operation (proportion and integration operation). The sin² θ₁ generation section 22 receives the power voltage v, as an input, and outputs a signal sin² θ₁ which is in synchronism with the power voltage v₁. The multiplication section 23 obtains a product of the signal sin² θ₁ and the value |i_(q)*|, and outputs the product as the q-axis current command i_(q)*. The i_(d)* operation section 24 receives the DC voltage V_(dc), q-axis current i_(q) and motor real speed ω_(m) as inputs, and outputs a d-axis current command i_(d)* which is obtained by carrying out the operation of the equation (2). The PI sections 25 and 26 for d-axis and q-axis receive the deviations between the dq-axis current commands i_(d)* and i_(q)* and the dq -axis real currents i_(d) and i_(q), as inputs, and output first dq-axis voltage commands v_(d)*′ and v_(q)*′ which are obtained by carrying out the PI operations. The decoupling controlling section 27 receives the first dq-axis voltage commands v_(d)*′ and v_(q)*′ as inputs and outputs second dq-axis voltage commands v_(d)* and v_(q)* which are obtained by carrying out the operation of the equation, (3). The above arrangement is similar to the arrangement of a conventional inverter controlling apparatus.

[0115] And, the inverter controlling apparatus of FIG. 3 further comprises an i₁ command operation section 28, subtraction section 29, and P operation section 20. The i₁ command operation section 28 receives the average torque T_(m), maximum value V_(max) of the DC voltage and the coefficient η as inputs, and outputs a power current command value i₁* which is obtained by carrying out the operation of the equation (10). The subtraction section 29 subtracts the power current command value i₁* from the real current i₁. The P operation section 20 receives the output from the subtraction section 29, and outputs a q-axis current for correction which is obtained by carrying out the P operation. The deviation between the q -axis current command i_(q)* and the q-axis real current i_(q), is subtracted by the q-axis current for correction, and the subtraction result is supplied to the PI operation section 26.

[0116] Therefore, even when this inverter controlling apparatus is employed, current for torque can be controlled for suppressing capacitor current. Distortion in power current can also be decreased.

[0117]FIG. 4 is a block diagram illustrating a main section of an inverter controlling apparatus of a further embodiment according to the present invention. This inverter controlling apparatus is an apparatus which carries out feed-forward controlling.

[0118] This inverter controlling apparatus comprises a conventional condenser-less inverter controlling section 11 for outputting a provisional torque command or provisional current for torque for controlling a conventional condenser-less inverter, a capacitor current operation section 31, conversion section 32, and subtraction section 33. The capacitor current operation section 31 receives the power current i₁ and DC voltage v_(dc) as inputs, and carries out operation so as to obtain a capacitor current i_(c). The conversion section 32 receives the capacitor current i_(c), coefficient η, power voltage V₁, and rotational speed ω_(m) of the motor as inputs, and transforms the capacitor current i_(c) into a torque command or current command for torque for correction. The subtraction section 33 subtracts the torque command or current command for torque for correction output from the conversion section 32 from the provisional torque command or provisional current for torque output from the conventional condenser-less inverter controlling section 11, so that a final torque command or final current command for torque is obtained.

[0119] Operation of the inverter controlling apparatus is as follows.

[0120] When the feed-forward controlling is carried out, it is sufficient that the equation (9) is rewritten as an equation (11), and that a torque τ_(c) is overlapped to the torque command, the being in phase which torque τ_(c) is reverse to that of the capacitor current i_(c).

τ_(m) , T _(m)·sin² θ₁+τ_(c)  Equation (11)

[0121] Wherein, the torque τ_(c) is sufficient to be a torque which is expressed by an equation (12) which is based upon the equations (6) to (8). $\begin{matrix} {\tau_{c} = {{{- \frac{{{sign}\left( v_{1} \right)} \cdot v_{1} \cdot i_{c}}{\omega_{m}}} \cdot \eta} = {{- \frac{{v_{1}} \cdot i_{c}}{\omega_{m}}} \cdot \eta}}} & {{Equation}\quad (12)} \end{matrix}$

[0122] More specifically, when the capacitance of the capacitor is not 0, the power current i₁ can be expressed as an equation (13).

i ₁ =i ₁ ′+i _(c)*sign(v ₁)  Equation (13)

[0123] Wherein, i₁′ represents the power current when the capacitance of the capacitor is. 0, and is given by the equation (10). Further, sign( ) is a function which returns a sign.

[0124] Torque becomes the equation (12) from the relationship between the equation (6) and the equation (7), the torque negating the power item including the capacitor current i_(c) among results obtained by substituting the equation (13) for the equation (8).

[0125] Wherein, the coefficient η is a constant for taking account of main circuitry efficiency, motor efficiency, and power factor. The constant may be changed for determining distortion to be none, responding to the load torque and rotational speed. For simplification in the controlling and operating processing, the constant may be represented with a value at a typical load condition by taking a driving condition of an application device into consideration, for example.

[0126] Then, a case is described by talking an IPM motor disclosed in the Article 2 as an example, in which case a torque is controlled using current controlling. A torque τ_(m) of an IPM motor is represented by an equation (14).

τ_(m) =n·(λ _(a)+(L _(d) −L _(q))·i _(d))·i_(q)  Equation (14)

[0127] The item of (L_(d)-L_(q))

i_(d) in the equation (14) changes depending upon the d-axis current. When the assumption is made for simplification that the change width og the d-axis current is small and that the torque is in proportion to the d-axis current, the q-axis current command i_(q)*{refer to equation (15)} is obtained from the equation (9) and the equation (14).

i _(q) *=|i _(q)*|·sin² θ₁  Equation (15)

[0128] On the other hand, in the contrary, the inverter controlling apparatus calculates the q-axis current command i_(q)* based upon an equation (16) which is obtained from the equation (11) using the equation (14). $\begin{matrix} {i_{q}^{*} = {{{{i_{q}^{*}} \cdot \sin^{2}}\theta} - {\frac{v_{1} \cdot i_{c}}{\omega_{m}} \cdot \eta \cdot \frac{1}{n \cdot \left( {\lambda_{a} + {\left( {L_{d} - L_{q}} \right) \cdot I_{d0}}} \right)}}}} & {{Equation}\quad (16)} \end{matrix}$

[0129] The second item in the equation (16) represents the current for torque for compensating the capacitor current. Further, I_(do) represents a moving average value of the d-axis current for about {fraction (1/2)} to 10 cycles of the power waveform.

[0130] Therefore, the current for torque can be controlled for suppressing the capacitor current. And, the distortion in the power current can be reduced.

[0131] In FIG. 4, the arrangement is employed in which the capacitor current i_(c) is calculated from the detection value of the power current i₁ or DC voltage v_(dc). But, an arrangement may be employed in which a current sensor is provided for directly detecting the capacitor current i_(c), and the detection value is directly supplied to the conversion section 32.

[0132]FIG. 5 is a block diagram illustrating an inverter controlling apparatus of a further embodiment according to the present invention.

[0133] This inverter controlling apparatus differs from the inverter controlling apparatus of FIG. 3 in that a capacitor current operation section 31 and capacitor current compensation operation section 32′ are employed instead the i₁ command operation section 28, subtraction section 29 and P operation section. The capacitor current operation section 31 receives the power current i₁ or DC voltage v_(dc) as an input and carries out the operation for obtaining the capacitor current i₁. The capacitor current compensation operation section 32′ receives the capacitor current i_(c), power voltage v₁ and motor rotational speed ω_(m) as inputs, and converts the capacitor current i_(c) into the torque command for correction or current for torque command for correction.

[0134] Therefore, in this inverter controlling apparatus, the current for torque can be controlled for suppressing the capacitor current, and the distortion in the power current can be reduced.

[0135]FIG. 6 is a block diagram illustrating a main section of an inverter controlling apparatus of a further embodiment according to the present invention.

[0136] In this inverter controlling apparatus, an FFT (harmonics analysis) operation section 31 a and waveform generation section 31 b constitute the capacitor current operation-section 31 in FIG. 5.

[0137] The FFT operation section 31 a receives the absolute value |i₁| of the power current calculated by an absolute value operation section 31 f and the absolute value phase θ₂(=2

θ₁) (θ₂ is determined its 0 phase to be at a peak point of the absolute value |v₁| of the power voltage as is illustrated in FIG. 25) as inputs, carries out the FFT operation, and outputs amplitude components |i_(ch1)|, |i_(ch2)|,

of the harmonics i_(ch1), i_(ch2),

which are in-phase of −sin θ₂ corresponding to the capacitor current i_(c). The waveform generation section 31 b receives the amplitude components |i_(ch1)|, |i_(ch2)|,

of the harmonics i_(ch1), i_(ch2),

and the absolute value phase θ₂ as inputs, and generates the capacitor current i_(c) based upon an equation (17);

i _(c)=−|i_(ch1)|·sin θ₂ −|i _(ch2) |·sin 2θ₂ |i _(ch3)|·sin 3θ₂  Equation (17)

[0138] Therefore, when this inverter controlling apparatus is employed, the capacitor current i_(c) can be calculated accurately, the current for torque can be controlled for suppressing the capacitor current, and the distortion in the power current can be reduced.

[0139]FIG. 7 is a block diagram illustrating a main section of an inverter controlling apparatus of a further embodiment according to the present invention.

[0140] This inverter controlling apparatus differs from the inverter controlling apparatus of FIG. 6 in that a waveform generation section 31 c is employed instead the waveform generation section 31 b. The waveform generation section 31 c receives only the amplitude components |i_(ch1)| of the harmonics i_(ch1), i_(ch2),

of twice frequency with respect to the power frequency and absolute value phase 2

θ₁ of the power voltage, and generates the capacitor current i_(c). Of course, a device for outputting only the twice frequency component with respect to the power frequency may be employed as the FFT operation section 31 a.

[0141] As is understood from the equation (4), harmonic amplitude of the DC voltage v_(dc) decreases following the increase in harmonic order n. Therefore, the capacitor current i_(c) can be generated with considerably high accuracy even when the order is determined to be only the twice frequency with respect to the power frequency, the order being applied the FFT, as is illustrated in FIG. 7. Therefore, when this inverter controlling apparatus is employed, the operation load can be greatly reduced, the capacitor current i_(c) can be calculated accurately, the current for torque can be controlled for suppressing the capacitor current, and the distortion in the power current can be reduced.

[0142]FIG. 8 is a block diagram illustrating a main section of an inverter controlling apparatus of a further embodiment according to the present invention.

[0143] This inverter controlling apparatus differs from the inverter controlling apparatus of FIG. 6 in that a capacitor current pattern storage section 31 d is employed instead the FFT operation section 31 a and waveform generation section 31 b.

[0144] The capacitor current pattern storage section 31 d stores previously operated capacitor current is based upon the equation (5), and carries out looking-up operation based upon the absolute value phase 2

θ₁ of the power voltage.

[0145] Therefore, the operation load can be minimized, the capacitor current i_(c) can be calculated accurately, the current for torque can be controlled for suppressing the capacitor current, and the distortion in the power current can be reduced.

[0146]FIG. 9 is a block diagram illustrating a main section of an inverter controlling apparatus of a further embodiment according to the present invention.

[0147] This inverter controlling apparatus differs from the inverter controlling apparatus of FIG. 8 in that a capacitor current correction section 31 e is further included. The capacitor current correction section 31 e receives the capacitor current i_(c)′ output from the capacitor current pattern storage section 31 d, and the difference between the maximum value V_(max) and the minimum value V_(min) of the DC voltage v_(dc) as inputs, carries out an operation of an equation (18), and corrects the capacitor current. $\begin{matrix} {i_{c} = {\frac{V_{\max} - V_{\min}}{V_{\max}} \cdot {i_{c}}^{\prime}}} & {{Equation}\quad (18)} \end{matrix}$

[0148] Operation of the inverter controlling apparatus having this arrangement is described with reference to FIG. 10.

[0149]FIG. 10(A) illustrates a waveform of the DC voltage v_(dc) when the minimum value of the DC voltage v_(dc) is determined to be v_(min) by the field controlling, while FIG. 10(B) illustrates a waveform of the DC voltage V_(dc) when load is light.

[0150] That is, an amplitude of harmonic component of the DC voltage V_(dc) changes depending upon load and controlling condition, as is understood from FIG. 10.

[0151] In the inverter controlling apparatus of FIG. 9, the capacitor current is corrected by carrying out the operation of the equation: (18) by the capacitor current correction section 31 e. Therefore, the capacitor current can be obtained with accuracy and with simple operation despite the load and controlling condition, the current for torque can be controlled for suppressing the capacitor current, and the distortion in the power current can be reduced.

[0152]FIG. 11 is a block diagram illustrating a main section of an inverter controlling apparatus of a further embodiment according to the present invention.

[0153] This inverter controlling apparatus differs from the inverter controlling apparatus of FIGS. 3 and 5 in that a subtraction section 22 a is further included. The subtraction section 22 a subtracts the phase ξ for correction (q-axis current phase command) from the phase θ₁ of the power voltage so as to obtain a corrected phase θ, and supplies the corrected phase θ to the sin² θ generation section 22.

[0154] Operation of the inverter controlling apparatus having this arrangement is as follows.

[0155] When θ is small, cos θ is approximated to be 1, and sin θ is approximated to be 0. Therefore, relationship of an equation (19) is obtained.

sin²(θ₁+ξ)=sin² θ₁−ξ·sin 2θ₁  Equation (19)

[0156] The second item of the equation (19) becomes opposite phase of the capacitor current i_(c) when ξ is determined to be delay phase, that is negative, and its amplitude can be controlled based upon the magnitude |ξ| of the q-axis current phase command.

[0157] Therefore, the capacitor current i_(c) can be compensated more easily, by employing the arrangement of FIG. 11.

[0158]FIG. 12 is a flowchart explaining power phase synchronism processing. The processing is started in response to the rising of the power voltage (rising of the zero-cross detection signal for the input voltage). In step SP1, a phase angle θ₁(j) is set to be 0. Then, the processing returns to the original processing. Herein and hereinafter, the suffix (j) is used to recognize a sample point.

[0159]FIG. 13 is a flowchart explaining power phase generation processing. The processing is started at predetermined interruption interval T_(s). In step SP1, a phase angle θ₁(k−1) is input. In step SP2, a phase angle θ₁(k) at the present time is generated by carrying out the operation of θ₁(k)=θ₁(k−1)+Δθ. Then, the processing returns to the original processing.

[0160] The constant Δθ is determined as follows, for example.

[0161] When the power frequency f₁=50 Hz, and when assumption is made that θ₁=3600 is the power phase of 360° and that the interruption interval T_(s) is 200 μs, Δθ(=θ₁

f₁

T_(s)) becomes 36.

[0162]FIG. 14 is a flowchart explaining current controlling processing. The processing is carried out at every predetermined interruption interval T_(s).

[0163] In step SP1, the rotational position signal θ_(m)(n), rotational speed ω_(m)(n), DC voltage v_(dc)(n), and motor currents i_(u)(n), i_(v)(n) and i_(w)(n) are input (n is an integer which is incremented at every processing). In step SP2, transformation operation processing from three-phase to dq-coordinates is carried out so as to calculate the dq-axis currents i_(d)(n) and i_(q)(n). In step SP3, dq-axis command current operation processing is carried out. In step SP4, dq-axis current commands i_(d)(n)* and i_(q)(n)* are input. In step SP5, operations of ε_(d)(n)=i_(d)(n)*−° i_(d)(n) and ε_(q)(n)=i_(q)(n)*−i_(q)(n) are carried out so as to calculate dq-axis current deviation ε_(d)(n) and ε_(q)(n).

[0164] In step SP6, operations of v_(d)′(n)=K_(pd)

ε_(d)(n)+K_(id)

Σε_(d)(n) and v_(q)′ (n)=K_(pq)

ε_(q)(n)+K_(iq)

Σε_(q)(n) are carried out so as to perform PI operations for dq-axis voltage. In step SP7, decoupling controlling operation of [v_(d)(n)=v_(d)′(n)−L_(q)

i_(q)(n)

n

ω_(m) and v_(q)(n)=v_(q)′(n)+{λ_(a)+L_(d)

i_(d)(n)}

n

ω_(m)] are carried out so as to calculate dq-axis voltage commands v_(d)(n) and v_(q)(n). In step SP8, conversion operation processing from d-q to three-phase coordinates is carried out so as to calculate voltage command for each phase v_(u)(n)*, v_(v)(n)*, and v_(w)(n)*. In step SP9, operation of an equation (20) is carried out so as to calculate pulse width for each phase τ_(u)(n+1), τ_(v)(n+1), and τ_(w)(n+1), and to store the pulse width in a PWM timer. Then, operation returns to the original processing.

τ_(u)(n+1)=[{v _(u)(n)*/v _(dc)(n)}+½]·T _(c)

τ_(v)(n+1)=[{v _(v)(n)*/v _(dc)(n)}+½]·T _(c)

τ_(w)(n+1)=[{v _(w)(n)*/v _(dc)(n)}+½]·T _(c)  Equation (20)

[0165] Next, the operation in step SP3 in FIG. 14 is described.

[0166]FIG. 15 is a flowchart explaining a conventional operation in step SP3 in FIG. 14.

[0167] In step SP1, the power phase θ₁(n) and q-axis current average value command |i_(q)(n)*| are input. In step SP2, operation of i_(q)(n)*=|i_(q)(n)*|·sin² θ₁(n) is carried out so as to calculate the q-axis current command i_(q)(n)*. In step SP3, operation of i_(d)(n)*=−λ_(a)/L_(d)+(1/L_(d))[{v_(dc)/n/ω_(m)(n)}²−{L_(q)

i_(q)(n)}²]^(1/2) is carried out so as to calculate the d-axis current command i_(d)(n)*. Then, operation returns to the original processing.

[0168] Therefore, compensation of the capacitor current cannot be carried out.

[0169]FIG. 16 is a flowchart explaining an operation of an example according to the present invention in step SP3 in FIG. 14.

[0170] In step SP1, the power phase θ₁(n), q-axis current average value command |i_(q)(n)*|, and capacitor current i_(c)(n) are input. In step SP2, operation of i_(q)(n)*=|i_(q)(n)*|

sin² θ₁(n)−i_(c) is carried out so as to calculate the q-axis current command i_(q)(n)*. In step SP3, operation of i_(d)(n)*=−λ_(a)/L_(d)+(1/L_(d))[{v_(dc)/n/ω_(m)(n)}²−{L_(q)

i_(q)(n)}²]^(1/2) carried out so as to calculate the d-axis current command i_(d)(n)*. Then, operation returns to the original processing.

[0171] Therefore, compensation of the capacitor current can be carried out.

[0172]FIG. 17 is a flowchart explaining an operation of another example according to the present invention in step SP3 in FIG. 14.

[0173] In step SP1, the power phase θ₁(n), q-axis current phase command ξ(n), and q-axis current average value command |i_(q)(n)*| are input. In step SP2, operation of i_(q)(n)*=|i_(q)(n)*|

sin² θ₁(n)−ξ(n) is carried out so as to calculate the q-axis current command i_(q)(n). In step SP3, operation of i_(d)(n)*=−λ_(a)/L_(d)+(1/L_(d))[{v_(dc)/n/ω_(m)(n)}²−{L_(q)

i_(q)(n)}²]^(1/2) is carried out so as to calculate the d-axis current command i_(d)(n). Then, operation returns to the original processing.

[0174] Therefore, compensation of the capacitor current can be carried out more easily.

[0175] The invention of claim 1 has a characteristic effect that harmonics in power current can be reduced.

[0176] The invention of claim 2 has an effect which is similar to that of claim 1, by carrying out the torque controlling for a motor, speed controlling for a motor or the like.

[0177] The invention of claim 3 has an effect which is similar to that of claim 1, by carrying out the controlling of torque or current for torque.

[0178] The invention of claim 4 has a characteristic effect that harmonics in power current can be reduced.

[0179] The invention of claim 5 has a characteristic effect that harmonics in power current can be reduced.

[0180] The invention of claim 6 has an effect which is similar to that of claim 5, by carrying out the torque controlling for a motor, speed controlling for a motor or the like.

[0181] The invention of claim 7 has an effect which is similar to that of claim 5, by carrying out the controlling of torque or current for torque.

[0182] The invention of claim 8 has a characteristic effect that harmonics in power current can be reduced by negating the capacitor current.

[0183] The invention of claim 9 has an effect which is similar to that of claim 8.

[0184] The invention of claim 10 has a characteristic effect that the operation load can be reduced, in addition to the effect which is similar to that of claim 9.

[0185] The invention of claim 11 has a characteristic effect that the operation load can be reduced, in addition to the effect which is similar to that of claim 8.

[0186] The invention of claim 12 has a characteristic effect that the capacitor current can be calculated with accuracy, in addition to the effects which are similar to those of claim 11.

[0187] The invention of claim 13 has a characteristic effect that the compensation of the capacitor current can be carried out easily, in addition to the effect which is similar to that of claim 7. 

What is claimed is:
 1. An inverter controlling method is a method which includes a single-phase rectification circuitry (2) and three-phase inverter (4), determines a capacitance of a capacitor (3) connected between output terminals of the single-phase rectification circuitry (2) for allowing an output voltage of the single-phase rectification circuitry (2) to pulsate at twice frequency with respect to a power frequency, and controls the three-phase inverter (4) for supplying output voltages or output currents from the three-phase inverter (4) to a motor (5), the method is characterized in that the method comprising a step of carrying out controlling for suppressing a current flowing into the capacitor (3) from a power source via the single-phase rectification circuitry (2).
 2. An inverter controlling method as set forth in claim 1, wherein the method controls the motor (5) for suppressing a current flowing into the capacitor (3) from a power source via the single-phase rectification circuitry (2).
 3. An inverter controlling method as set forth in claim 1, wherein the method controls a torque or current for torque for suppressing a current flowing into the capacitor (3) from a power source via the single-phase rectification circuitry (2).
 4. An inverter controlling apparatus is an apparatus which includes a single-phase rectification circuitry (2) and three-phase inverter (4), determines a capacitance of a capacitor (3) connected between output terminals of the single-phase rectification circuitry (2) for allowing an output voltage of the single-phase rectification circuitry (2) to pulsate at twice frequency with respect to a power frequency, and controls the three-phase inverter (4) for supplying output voltages or output currents from the three-phase inverter (4) to a motor (5), the apparatus is characterized in that the apparatus comprising suppression means for suppressing a current flowing into the capacitor (3) from a power source via the single-phase rectification circuitry (2).
 5. An inverter controlling apparatus is an apparatus which includes a single-phase rectification circuitry (2) and three-phase inverter (4), determines a capacitance of a capacitor (3) connected between output terminals of the single-phase rectification circuitry (2) for allowing an output voltage of the single-phase rectification circuitry (2) to pulsate at twice frequency with respect to a power frequency, and controls the three-phase inverter (4) for supplying output voltages or output currents from the three-phase inverter (4) to a motor (5), the apparatus is characterized in that the apparatus comprising controlling means (12)(13)(14)(20)(22 a)(28)(29)(31)(31 a)(31 b)(31 c)(31 d)(31 e)(32)(32′)(33) for carrying out controlling for suppressing a current flowing into the capacitor (3) from a power source via the single-phase rectification circuitry (2).
 6. An inverter controlling apparatus as set forth in claim 5, wherein the controlling means (12)(13)(14)(20)(22 a)(28)(29)(31)(31 a)(31 b)(31 c)(31 d)(31 e)(32)(32′) (33) controls the motor (5) for suppressing a current flowing into the capacitor (3) from a power source via the single-phase rectification circuitry (2)
 7. An inverter controlling apparatus as set forth in claim 5, wherein the controlling means (12)(13)(14)(20)(22 a)(28)(29)(31)(31 a)(31 b)(31 c)(31 d)(31 e)(32)(32′) (33) controls a torque or current for torque for suppressing a current flowing into the capacitor (3) from a power source via the single-phase rectification circuitry (2)
 8. An inverter controlling apparatus is an apparatus which includes a single-phase rectification circuitry (2) and three-phase inverter (4), determines a capacitance of a capacitor (3) connected between output terminals of the single-phase rectification circuitry (2) for allowing an output voltage of the single-phase rectification circuitry (2) to pulsate at twice frequency with respect to a power frequency, and controls the three-phase inverter (4) for supplying output voltages or output currents from the three-phase inverter (4) to a motor (5), the apparatus is characterized in that the apparatus comprising: Capacitor current operation means (31)(31 a)(31 b)(31 c)(31 d) for calculating a capacitor current flowing into the capacitor (3) from a power source via the single-phase rectification circuitry (2); and Current for torque correction means (32)(32′)(33) for correcting a current for torque by subtracting the obtained capacitor current from the current for torque.
 9. An inverter controlling apparatus as set forth in claim 8, wherein the capacitor current operation means (31 a) carries out the harmonic analysis of the power current.
 10. An inverter controlling apparatus as set forth in claim 9, wherein a harmonic component of a twice frequency with respect to the power frequency is employed as the harmonic analysis result.
 11. An inverter controlling apparatus as set forth in claim 8, wherein the capacitor current operation means (31 d) outputs the capacitor current based upon stored pattern.
 12. An inverter controlling apparatus as set forth in claim 11, further comprising correction means (31 e) for correcting the capacitor current output based upon stored pattern, based upon a direct current voltage detection value.
 13. An inverter controlling apparatus as set forth in claim 7, wherein the controlling means (22 a) includes phase determination means (22 a) for determining a phase of the current for torque to be a delayed phase. 